Electrical resistor



Jan- 7, 1964 M. E. BoURNs Re 25,510

ELECTRICAL RESISTOR Original Filed July 5, 1955 y wir@ a 7 2 BY r ATTORNEYS.

United States Patent Office Re. 25,510 Reissued Jan. 7, 1964 25,510 ELECTRICAL RESISTOR Marlan E. Bourns, 2530 Piedmont Drive, Riverside, Calif.

Original No. 2,952,825, dated Sept. 13, 1960, Ser. No. 839,978, Sept. 14, 1959, which is a continuation of abandoned application Ser. No. 519,847, July 5, 1955. Application for reissue Nov. 30, 1961, Ser. No. 157,302

Claims. (Cl. 338-150) Matter enclosed in heavy brackets appears in the original patent but forms no part of this reissue specification; matter printed in italics indicates the additions made by reissue.

The present invention relates to new and improved electrical components and is a continuation of my now abandoned application, Serial No. 519,847, filed July 5, 1955, entitled Electrical Resistor" (as amended by Examiner). More specifically, it relates to new and improved electrical potentiometers and like devices.

A great many organizations at the present time are devoting considerable time and money to the development of various electrical or electronic devices which consist primarily of a number of separate electrical components secured together in a compact assembly capable of being used as an integral unit in a large device, such as for example, a computer or the like. One particular effort along these lines has been financed to a large extent by the United States Air Force and is commonly termed Project Tinker T oy." In this Tinker Toy Project, the electrical components utilized are in the form of small flat squares approximately 3A of an inch in length along each edge and of varying thickness. Each of the com ponents in this type of a structure is secured within an elongated cage consisting of l2 wires, three of which are disposed along each edge of each component. All of the wires used are located parallel to one another. At times, less than twelve wires are employed, and discontinuous wires are employed in order to make or complete a desired electrical circuit.

As nearly as is known at the present time, no potentiometers or like electrical components of essentially an adjustable nature have been developed which are capable of being used satisfactorily in the so-called Tinker Toy Project. It is a broad object of this invention to provide adjustable potcntiometers and resistors which can be satisfactorily utilized in the so-called Tinker Toy type of construction. Another object of the instant invention is to provide adjustable electrical components of the class described which are capable of wide use in other diverse applications and which may be easily manufactured with a minimum of difficulty. A further object of this invention is to provide small electrical components of the category indicated which are rugged so that they are capable of standing a large amount of abuse. Another object of this disclosure is to teach the manufacture and construction of potentiometers and the like which may be directly secured to various wires in an electrical circuit, and which may be supported in a desired position by these wires.

Further objects of this disclosure as well as many other advantages of the constructions described herein will be apparent from the remainder of this description, including the appended claims and the accompanying drawings, in which:

FIG. l is an isometric view of a potentiometer of the present invention;

FIG. 2 is a cross sectional view taken at line 2-2 of FIG. l;

FIG. 3 is a cross sectional view taken at line 3 3 of FIG. l;

FIG. 4 is an isometric view of a member utilized in the potentiometer shown in FIG. l;

FIG. 5 is a view similar to FIG. 3 of a modified potentiometer of the invention;

FIG. 6 is a cross sectional view taken at line 6-6 of FIG. 5;

FIG. 7 is a side view of a second modified potentiometer of the invention;

FIG. 8 is a cross sectional view taken at line 8-8 of FIG. 7; and

FIG. 9 is a cross sectional View taken at line 9 9 of FIG. 8.

It is to be understood that the accompanying drawings are not scaled to any precise commercial unit but are designed merely to illustrate the essential, preferred features of the present invention. Wherever convenient for purposes of illustration and explanation, like numerals have been utilized to designate like parts.

The present invention is defined in detail by the appended :claims `forming a part of the specification. It desired, however, the present invention may be brietly summarized as required by the Rules of Practice of the United States Patent Office as being primarily concerned with new and improved electrical instruments or components which include: a housing; means defining a disc shaped cavity within said housing; first and second electrical means disposed within said cavity; a movable member located within said cavity; means for rotating said movable member within said cavity, said means projecting to the exterior of said housing and being located at one side of said cavity; means attached to said movable member for electrically connecting said first and second electrical means; and means for connecting said first and second electrical means into an electrical circuit, said means being electrically connected to said rst and second electrical means and projecting to the exterior of said housing.

The details of the invention are best explained directly by reference to the accompanying drawings. In FIGS. l through 3 of the drawings there is shown an adjustable potentiometer 10 of the invention which includes a base 12 and a cover 14 positioned upon this base. It is to be noted that both the base 12 and the cover 14 are of roughly the same exterior shape as a small square wafer and that the exterior dimensions of the cover 14 are smaller than the exterior dimensions of the base 12 so that part of the upper surface 16 of the base 12 is exposed when the cover is located on it. The base 12 and the cover 14 are preferably formed out of a non-conductive material such as, for example, a suitable phenolic material or a dielectric ceramic. These two members are put together by suitable conventional means such as, for example, an adhesive, so as to define an internal cavity 18 of disc like shape between them.

The upper surface 16 of the base 12 is of flat configuration and includes an arcuate resistance strip 20 formed out of appropriate conventional material such as, for example, a resistance ink. The ends of this resistance strip are overlaid by parts of terminals 22 and 24. These terminals are preferably formed of a silver ink or the like and extend from the resistance strip 2l) to adjacent edges 26 of the base 12 so that they may be readily connected to various wires or other means used to electrically connect the potentiometer 10 into a circuit. Within the center of the arcuate resistance strip 20 there is located upon the upper surface 16 a circular end 28 of a terminal 30 an electrical return which is similar to the terminals 22 and 24 and which projects to adjacent edge 26 of the base 12.

Disposed along the edges 26 of the base 12 and edges 32 of the cover 14 are a series of grooves 34 which are speciiically designed to hold the various wires such as, for example, wires employed in the so-called Tinker Toy type of construction when the potentiometer' 10 is mounted in this type of an assembly. With this construction the various terminals 22, 24, and 30 may be secured directly to these wires by solder or other like means as desired so that as a double headed screw 36 disposed within a slot 38 within the cover 14 is turned a disc 40 located within the cavity 18 is turned, placing resilient contacts 42 and 44 in engagement with different portions of the resistance strip 20 and with the same portion of the circular end 28 at the terminal 34. This construction is best understood with reference to FIGS. 3 and 4 of the drawings.

The screw 36 is provided with grooves 46 which are designed to be engaged by projections 48 formed upon the cover 14 within the slot 38 so as to hold this screw in position with the threads 50 on it projecting a short distance through an opening 52 in the cover 14 connecting the slot 38 and the cavity 18. Thus, with this construction the threads 50 are located within the cover 14 so as to engage with what are in efect gear teeth 54 formed on the periphery of the disc 40. The contacts 42 and 44 are formed out of the disc 40 by a simple punching operation so as to include ends 56 and 58, respectively, which are designed to engage the resistance strip 20 and the circular end 28. The disc 40 is preferably formed out of a compartively strong resilient metal such as, for example, brass, by a simple metal stamping operation, and is of such a dimension as to fit closely within the cavity 18. The contact 44 normally holds this disc 40 in a desired position within the cavity 18 parallel to the surface 16. The screw 36 is preferably formed out of such non-conductive materials as nylon or the like, and is located at the side of the cavity 18.

In FIG. of the drawings a modified potentiometer 60 of the invention is shown which differs from the potentiometer solely in that the disc 40 previously described is replaced by a ring 62 having gear teeth 64 such as the teeth 54 formed on the outer periphery thereof. Within this ring is held a resilient metal contact ring 66 of partially circular shape having formed thereon resilient contact arms 68 and 70 engaging the resistance strip 20 and the circular end 28. With this construction the contact ring 66 is preferably larger than 180 of a circle so that it may be easily held in position within the ring 62 by spring tension. If desired, the contact ring 66 may be secured to the ring 62 by the use of rivets or an adhesive. The ring 62 may be formed either out of metal or of a non-conductive material such as, for example, phenolic resin. In the latter preferred case it is possible to form the screw 36' shown in this figure out of metal.

Those skilled in the art will realize that all of the parts of the potentiometer 60 which are the same as the various parts of the potentiometer 10 previously described are identified in FIGS. 5 and 6 of the drawings by the primes of the same numerals used earlier in this description.

In FIGS. 7, 8, and 9 of the drawings a second modilied potentiometer of the invention 72 is illustrated which includes a base 74, a spacer 76 and a cover 78. All of these three members are preferably formed out of a nonconductive material such as, for example, a ceramic or a phenolic resin in such a manner that the edges 80 of the spacer 76 are shorter than the edges 82 of the base 74 and the cover 78. Appropriate grooves or notches 84, similar to the grooves 34 previously described, are provided in the edges 80 and 82 for the same purpose as the grooves 34. The base 74, spacer 76 and the cover 78 may be attached to one another in any convenient manner such as, for example, through the use of an adhesive or the use of rivets so as to form a composite sandwich-like construction as illustrated.

Within the spacer 76 there is located a circular opening 86 which in the sandwich-like construction serves to dene together with the base 74 and the cover 78 a cavity 88 such as the cavity 18 previously described.

On thc top surface 90 of the base 74 there is provided a resistance strip 20 similar to the resistance strip 20 and terminals 22 and 24' similar to the terminals 22 and 24 previously described, and a terminal 30' similar t0 the terminal 30 previously described. This latter terminal includes instead of the circular end 28 a ring shaped end 92 located within the resistance strip 20 s0 as to be concentrically located with respect to this resistance strip.

Within the base 74 and the cover 78 there are located aligned cylindrical holes 94 which are designed to carry a pin 96 serving as a shaft, whereby a metal disc 98 attached to this pin by solder or the like may be rotated about this pin through the operation of a small gear 100. The gear 100 is mounted similarly to the disc 98 about a pin 102 located within aligned holes (not shown) in the base 74 and the cover 78 so as to be held normally within an opening 106 in the spacer 76 so that the teeth formed upon the gear 100 can coact with gear teeth 108 formed on the periphery of the disc 98 and so that the gear 100 is at one side of the cavity 88. Contacts 110 and 112 are formed on the disc 98 in a similar manner to the manner in which the contacts 42 and 44 are formed on the disc 40 in order to engage the resistance strip 20' and the end 98 of the terminal 30' employed. The electrical conduction means employed on the base 74 are the same as those used in the potentiometer 60.

Those skilled in the art will realize both the modied potentiometers 60 and 72 can be connected to various wires in essentially the same manner as the potentiometer 10. All of these three different constructions are quite advantageous inasmuch as with them quite fine adjustment is possible through the use of what amounts to gear reduction means formed on the discs 40, 40', and 98 and on the screws 36, 36 and on the gear 100. These constructions are quite advantageous for assembly in complex electrical assemblies such as those of the so-called Tinker Toy project inasmuch as the means used to adjust them are relatively small and are located in such a manner as to not to interfere to any material extent with the com* plete assembly. Further, all of the potentiometers, 10, 60 and 72 are very thin, small devices Which are quite reliable in use and which can be quite easily constructed utilizing established techniques.

Obviously a number of changes may be made in this invention without departing from the essential features of it. As an example of such changes, the sandwich type of construction illustrated in FIGS. 7, 8, and 9 of the drawings could be utilized in forming the potentiometers 10 and 60. Further, the ring type of construction shown in FIG. 4 of the drawings may be utilized together with a small drixe gear such as the gear 100. All such modifications of this category are considered to be part of the present invention insofar as they are defined in the appended claims.

I claim:

1. A new and improved potentiometer which includes: a non-conductive base; a terminal serving as an electriv cal return mounted on said base, said terminal including a circular end centrally positioned upon said base; an arcuate electrical resistance strip mounted on said base concentric with said circular end; electrical terminals positioned upon said base, said electrical terminals being in electrical communication with the ends of said arcuate resistance strip; a cover positioned over said base, said cover including an opening formed therein so as to define an internal cavity of disc-like shape between said cover and said base; a resilient metal disc positioned within said cavity; means defining electrical contacts engaging said arcuate resistance strip and said circular end formed on said disc; gear teeth formed on the periphery of said disc; means defining a slot within said cover; a screw located within said slot, the threads of said screw engaging said gear teeth on said disc whereby as said screw is turned, said disc is rotated within said cavity.

2. An improved potentiometer comprising, in combination:

first means, including casing means, constructed and arranged to provide an inner chamber of generally circular configuration and to provide an opening of substantially circular cross-section, the opening extending from the exterior 0f said casing means into communication with the inner chamber provided by the casing means;

second means, including a peripherally toothed gear means constructed and arranged for rotation in the chamber provided by said casing means;

third means, comprising electrical means including a resistive element disposed in the chamber provided by said casing means and having an arcuate exposed contact portion, and including electrical conductor means connected to end portions of the resistive element for electrical connection thereto;

fourth means, including screw-threaded means rotatably disposed and conned in the opening provided by said casing means and constructed and arranged for cooperative engagement with the periphery of said gear means to rotate the latter incident to rotation of the screw-threaded means;

and fifth means, comprising movable electrical contact means in contact with the arcuate contact portion of said resistive element and constructed and arranged for rotation by said gear means to contact different portions of the resistive means, said fifth means comprising conductive means for providing an electrical connection to said movable electrical Contact means.

3. An improved miniature potentiometer, comprising:

first means, comprising upper and lower mating recessdehning casing members effective when assembled to provide a casing having an internal recess and gear-restricting means for restricting a gear in said recess to rotate about a given axis of rotation, and said casing including means dening an opening leading to said recess and for conning a screwthreaded means in said opening;

second means, including a screw-threaded means rotatably mounted in and conned in said opening and disposed with at least a portion of its screw thread exposed to the interior of said recess;

third means, comprising an externally-toothed gear means disposed in said recess and conned to rotation about the said given axis of rotation by said gear-restricting means and with teeth thereof in engagement with the screw thread of said screwthreaded means for rotation of the gear means incident t0 rotation of the screw-threaded means;

fourth means, comprising a resistive element having an arcuate contact-engaging surface exposed in said recess, said fourth means including electrical connections to the ends of said resistive element and extending to the exterior of said casing;

and fifth means, including means on said gear means and comprising movable contact means including a contact and constructed and arranged for movement of said contact along and in contact with the contactengaging surface of said resistive element,

whereby as said screw-threaded means is rotated said contact is moved along said resistive element to vary the resistance exhibited between said contact and either of said connections.

4. A potentiometer comprising:

rst means, comprising casing means constructed and arranged as a relatively thin substantially square housing comprising a base member and a second member, said casing means further being constructed and arranged to provide therein a cavity and also an opening of substantially circular crosssection extending from said cavity to the exterior of the casing means;

second means, comprising a rotatable worm means mounted in said opening for rotation therein and having a threaded portion exposed within said cavity;

third means, comprising rotatable means mounted in said cavity in said casing means and engaging the threaded portion of said worm means for rotation thereby incident upon rotation of said worm means;

fourth means, comprising curved resistance element means presenting an arcuate exposed contact face in coaxial relationship with said rotatable means in said chamber, and electrical connections to end-portions of said resistance clement means, said fourth means further comprising electrical return means; and fifth means, comprising contact means constructed and arranged for rotation by said rotatable means to wipe along said exposed contact face of said resistance element means and electrically interconnect the latter and said electrical return means, whereby upon rotation of said worm means the electrical resistance exhibited between said electrical return means and one of said electrical connections is varied.

5. A potentiometer comprising, in combination:

Jrst means, including casing means, constructed and arranged to provide a chamber of generally circular shape and further to provide an opening of substantially circular cross-section and which opening is arranged approximately tangentially with respect to a member of generally circular outline in said citantber and said opening extending from the exterior of said casing means into communication with the said chamber;

second means, comprising rotatable screw-threaded means disposed and confined in the said opening provided in said casing means with a screw-threaded portion thereof disposed in the region of tangency with the member of generally circular outline in said chamber;

third means, comprising a member of generally circular outline and rotatable about an axis and said member being disposed and confined in the said chamber and arranged in peripheral contact with tlze screw-thread of said screw-threaded means for rotation by the latter;

fourth means, comprising electrical means including a resistance element presenting an arcuate contact arca and disposed in the said circular chamber, said electrical means further comprising electrical connections to respective end portions of tlze resistance ele ment and also comprising electrical return means; and

fifth means, comprising contact means constructed and arranged to wipe upon the arcuate contact area of said resistance element and interconnect the latter with said electrical return means, said contact means further being constructed and arranged to be moved by said third means incident to rotation of said third means by said screw-threaded means upon rotation of the latter, whereby rotation of said screw-threaded means causes wiping movement of said contact means along the arcuate contact area of said resistance element to change the value of the electrical resistance exhibited between either 0f said electrical connections and said electrical return means.

References Cited in the file of this patent or the original patent UNITED STATES PATENTS 586,864 Pieper July 20, 1897 1,602,497 Livingston Oct. 12, 1926 2,197,312 Nelson Apr. 16, 1940 2,451,241 Rosentreter Oct. 12, 1948 2,541,682 Tellkamp July 11, 1950 2,565,434 Kocmich Aug. 21, 1951 2,704,316 De Bell Mar. 15, 1955 

